Thermally-assisted magnetic recording head

ABSTRACT

Thermally-assisted magnetic recording head, includes: a magnetic pole having an end exposed on an air-bearing surface; a waveguide; a plasmon generator having a first and second region, first region extending backward from the air-bearing surface to a first position, second region being coupled with the first region at the first position, extending backward from first position, and having a width in a track-width direction, and width in the track-width direction of second region being larger than a width in the track-width direction of first region; an adhesion layer having an end exposed on the air-bearing surface and a first adhesion region, the first adhesion region being in close contact with an end face in the track-width direction of first region; and a cladding layer located around plasmon generator and adhesion layer. Adhesion force between adhesion layer and plasmon generator is greater than adhesion force between cladding layer and plasmon generator.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a thermally-assisted magnetic recording headused in thermally-assisted magnetic recording in which near-field lightis applied to a magnetic recording medium to lower a coercivity thereofso as to record information.

2. Description of Related Art

In the past, a magnetic disk unit has been used for writing and readingmagnetic information (hereinafter, simply referred to as information).The magnetic disk unit includes, in the housing thereof for example, amagnetic disk in which information is stored, and a magnetic read writehead that records information into the magnetic disk and reproducesinformation stored in the magnetic disk. The magnetic disk is supportedby a rotary shaft of a spindle motor, which is fixed to the housing, androtates around the rotary shaft. On the other hand, the magnetic readwrite head is formed on a side surface of a magnetic head sliderprovided on one end of a suspension, and includes a magnetic writeelement and a magnetic read element that have an air bearing surface(ABS) facing the magnetic disk. In particular, as the magnetic readelement, a magnetoresistive (MR) element exhibiting MR effect isgenerally used. The other end of the suspension is attached to an end ofan arm pivotally supported by a fixed shaft installed upright in thehousing.

When the magnetic disk unit is not operated, namely, when the magneticdisk does not rotate and remains stationary, the magnetic read writehead is not located over the magnetic disk and is pulled off to theoutside (unload state). When the magnetic disk unit is driven and themagnetic disk starts to rotate, the magnetic read write head is changedto a state where the magnetic read write head is moved to apredetermined position over the magnetic disk together with thesuspension (load state). When the rotation number of the magnetic diskreaches a predetermined number, the magnetic head slider is stabilizedin a state of slightly floating over the surface of the magnetic diskdue to the balance of positive pressure and negative pressure, and thus,information is accurately recorded and reproduced.

In recent years, along with a progress in higher recording density(higher capacity) of the magnetic disk, improvement in performance ofthe magnetic read write head and the magnetic disk has been demanded.The magnetic disk is a discontinuous medium including collected magneticmicroparticles, and each magnetic microparticle has a single-domainstructure. In the magnetic disk, one recording bit is configured of aplurality of magnetic microparticles. Since it is necessary for theasperity of a boundary between adjacent recording bits to be small inorder to increase the recording density, it is necessary for themagnetic microparticles to be made small. However, if the magneticmicroparticles are made small in size, thermal stability of themagnetization of the magnetic microparticles is disadvantageouslylowered with decrease in volume of the magnetic microparticles. To solvethe issue, increasing anisotropy energy of the magnetic microparticle iseffective. However, increasing the anisotropy energy of the magneticmicroparticle leads to increase in coercivity of the magnetic disk, andas a result, difficulty occurs in the information recording in theexisting magnetic head.

As a method to solve the above-described difficulty, a so-calledthermally-assisted magnetic recording has been proposed. In the method,a magnetic disk with large coercivity is used, and when information iswritten, heat is applied together with the magnetic field to a sectionof the magnetic disk where the information is to be written to increasethe temperature and to lower the coercivity of that section, therebywriting the information. Hereinafter, the magnetic head used in thethermally-assisted magnetic recording is referred to as athermally-assisted magnetic recording head.

In performing the thermally-assisted magnetic recording, near-fieldlight is generally used for applying heat to a magnetic disk. Forexample, in Japanese Unexamined Patent Application Publication No.2001-255254 and in Japanese Patent No. 4032689, disclosed is atechnology of allowing frequency of light to coincide with a resonantfrequency of plasmons that are generated in a metal, by directlyapplying the light to a plasmon generator, in order to generatenear-field light. In the method of directly applying light to a plasmongenerator, however, the plasmon generator itself overheats andaccordingly deforms, depending on usage environment or conditions.Therefore, practical realization of the method is difficult.

Therefore, as a technology capable of avoiding such overheating, inJapanese Patent No. 4104584, a thermally-assisted head using surfaceplasmon polariton coupling is proposed. In this technology, withoutdirect irradiation of light propagating through a waveguide (guidedlight) to a plasmon generator, the guided light is coupled to theplasmon generator through evanescent coupling, and surface plasmonpolaritons generated on a surface of the plasmon generator are used.

In the thermally-assisted magnetic recording head using such surfaceplasmon polaritons, temperature increase of the plasmon generator issuppressed to some extent. However, it was confirmed that, when theplasmon generator is formed of Au (gold), deformation due to heat mayoccur in a small-volume section where the heat particularlyconcentrates, of the plasmon generator in the vicinity of theair-bearing surface.

SUMMARY OF THE INVENTION

When such deformation occurs, a tip section of the plasmon generator isreceded from the air-bearing surface and backs away from the magneticrecording medium. Therefore, it causes degradation of recordingperformance. Accordingly, it is desirable to provide athermally-assisted magnetic recording head capable of suppressingdeformation of a plasmon generator during operation and performingmagnetic recording with higher density.

A thermally-assisted magnetic recording head according to an embodimentof the present invention includes: a magnetic pole having an end exposedon an air-bearing surface; a waveguide; a plasmon generator having afirst region and a second region, the first region extending backwardfrom the air-bearing surface to a first position, the second regionbeing coupled with the first region at the first position, extendingbackward from the first position, and having a width in a track-widthdirection, and the width in the track-width direction of the secondregion being larger than a width in the track-width direction of thefirst region; an adhesion layer having an end exposed on the air-bearingsurface and a first adhesion region, the first adhesion region being inclose contact with an end face in the track-width direction of the firstregion; and a cladding layer located around the plasmon generator andthe adhesion layer. Here, adhesion force between the adhesion layer andthe plasmon generator is greater than adhesion force between thecladding layer and the plasmon generator.

A head gimbal assembly, a head arm assembly, and a magnetic disk unitaccording to respective embodiments of the present invention are eachprovided with the above-described thermally-assisted magnetic recordinghead.

In the thermally-assisted magnetic recording head, the head gimbalassembly including the same, the head arm assembly including the same,and the magnetic disk unit including the same according to therespective embodiments of the invention, the first adhesion region is inclose contact with the first region. Therefore, even when the volume ofthe first region whose temperature becomes relatively high duringoperation is smaller than the volume of the second region locatedbackward of the first region, agglomeration of the first region isdifficult to occur. On the other hand, since the first region and thesecond region are coupled with each other, the surface plasmonsgenerated by evanescent coupling between the light propagating throughthe waveguide and the second region efficiently propagates through thefirst region. Accordingly, even when the temperature increase of thefirst region of the plasmon generator occurs during operation, the firstregion of the plasmon generator is prevented from being receded from theair bearing surface, and near-field light is allowed to be efficientlygenerated. Consequently, magnetic recording with higher density becomespossible, and improvement of product lifetime is expected.

In this case, the adhesion layer may further include a second adhesionregion that is in close contact with an end face in the track-widthdirection of the second region. In addition, the first adhesion regionand the second adhesion region may be separated from each other, and asacrifice layer that is positioned between the first adhesion region andthe second adhesion region and faces a part of the end face in thetrack-width direction of the second region may be further included. Inthis case, the adhesion force between the adhesion layer and the plasmongenerator may be greater than adhesion force between the sacrifice layerand the plasmon generator. Further, the first adhesion region may covera top face of the first region, and the second adhesion region may covera top face of the second region.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a configuration of a magneticdisk unit provided with a magnetic read write head according to anembodiment of the invention.

FIG. 2 is a perspective view illustrating a configuration of a slider inthe magnetic disk unit illustrated in FIG. 1.

FIG. 3 is a sectional view illustrating a structure of a cross-sectionalsurface (YZ cross-sectional surface) orthogonal to an air bearingsurface, in the magnetic read write head illustrating in FIG. 2.

FIG. 4 is a sectional view illustrating a main part of the magnetic readwrite head illustrated in FIG. 3 in an enlarged manner.

FIG. 5 is a schematic diagram illustrating a shape in an XY plane of themain part of the magnetic read write head.

FIG. 6A is a schematic diagram illustrating a structure of an endsurface exposed on the air bearing surface, in the main part of themagnetic read write head.

FIG. 6B is a schematic diagram illustrating a structure of an endsurface exposed on the air bearing surface, in a main part of a magneticread write head according to a first modification.

FIG. 7 is a perspective view illustrating one process in a method ofmanufacturing the magnetic read write head illustrated in FIG. 1.

FIG. 8 is a perspective view illustrating one process following theprocess of FIG. 7.

FIG. 9 is a sectional view illustrating one process in the method ofmanufacturing the magnetic read write head illustrated in FIG. 1.

FIG. 10 is a sectional view illustrating one process following theprocess of FIG. 9.

FIG. 11 is a sectional view illustrating one process following theprocess of FIG. 10.

FIG. 12 is a sectional view illustrating one process following theprocess of FIG. 11.

FIG. 13 is a sectional view illustrating one process following theprocess of FIG. 12.

FIG. 14 is a block diagram illustrating a circuit configuration of themagnetic disk unit illustrated in FIG. 1.

FIG. 15 is a schematic diagram illustrating a shape in an XY plane of amain part of a magnetic read write head according to a secondmodification.

FIG. 16 is a schematic diagram illustrating a shape in an XY plane of amain part of a magnetic read write head according to a thirdmodification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of the invention will be described in detailwith reference to drawings.

[1. Configuration of Magnetic Disk Unit]

First, referring to FIG. 1 and FIG. 2, a configuration of a magneticdisk unit according to an embodiment of the present invention will bedescribed below.

FIG. 1 is a perspective view illustrating an internal configuration ofthe magnetic disk unit as the present embodiment. The magnetic disk unitadopts a load-unload system as a driving system, and includes, forexample, in a housing 1, a magnetic disk 2 as a magnetic recordingmedium in which information is to be written, and a Head Arm Assembly(HAA) 3 for writing information in the magnetic disk 2 and reading theinformation. The HAA 3 includes a Head Gimbals Assembly (HGA) 4, an arm5 supporting a base of the HGA 4, and a driver 6 as a power source forallowing the arm 5 to pivot. The HGA 4 includes a thermally-assistedmagnetic head device (hereinafter, simply referred to as a “magnetichead device”) 4A having a side surface provided with a magnetic readwrite head 10 (described later) according to the present embodiment, anda suspension 4B having an end provided with the magnetic head device 4A.The arm 5 supports the other end of the suspension 4B (an end oppositeto the end provided with the magnetic head device 4A). The arm 5 is soconfigured as to be pivotable, through a bearing 8, around a fixed shaft7 fixed to the housing 1. The driver 6 may be configured of, forexample, a voice coil motor. Incidentally, the magnetic disk unit hasone or a plurality of (FIG. 1 exemplifies the case of four) magneticdisks 2, and the magnetic head devices 4A are disposed corresponding torecording surfaces (a front surface and a back surface) of therespective magnetic disks 2. Each of the magnetic head devices 4A ismovable in a direction across write tracks, that is, in a track widthdirection (in an X-axis direction) in a plane parallel to the recordingsurfaces of each of the magnetic disks 2. On the other hand, themagnetic disk 2 rotates around a spindle motor 9 fixed to the housing 1in a rotation direction 2R substantially orthogonal to the X-axisdirection. With the rotation of the magnetic disk 2 and the movement ofthe magnetic head devices 4A, information is written into the magneticdisk 2 or stored information is read out. Further, the magnetic diskunit has a control circuit (described later) that controls a writeoperation and a read operation of the magnetic read write head 10, andcontrols emission operation of a laser diode as a light source thatgenerates laser light used for thermally-assisted magnetic recordingdescribed later.

FIG. 2 illustrates a configuration of the magnetic head device 4Aillustrated in FIG. 1. The magnetic head device 4A has a block-shapedslider 11 that may be formed of, for example, Al₂O₃·TiC (AlTiC). Theslider 11 may be substantially formed as a hexahedron, for example, andone surface thereof corresponds to an ABS 11S that is disposed inproximity to and to face the recording surface of the magnetic disk 2.When the magnetic disk unit is not driven, namely, when the spindlemotor 9 is stopped and the magnetic disk 2 does not rotate, the magnetichead device 4A is pulled off to the position away from an above part ofthe magnetic disk 2 (unload state), in order to prevent contact of theABS 11S and the recording surface. In contrast, when the magnetic diskunit is initiated, the magnetic disk 2 starts to rotate at a high speedby the spindle motor 9, the arm 5 is pivotably moved around the fixedshaft 7 by the driver 6, and therefore, the magnetic head device 4Amoves above the front surface of the magnetic disk 2, thereby being in aload state. The rotation of the magnetic disk 2 at a high speed causesair flow between the recording surface and the ABS 11S, and lift forcecaused by the air flow leads to a state where the magnetic head device4A floats to maintain a certain distance (magnetic spacing) along adirection (a Y-axis direction) orthogonal to the recording surface. Inaddition, on an element forming surface 11A that is one side surfaceorthogonal to the ABS 11S, the magnetic read write head 10 is provided.Incidentally, on a surface 11B opposite to the ABS 11S of the slider 11,a light source unit 50 is provided near the magnetic read write head 10.

[2. Detailed Structure of Magnetic Read Write Head]

Next, the magnetic read write head 10 is described in more detail withreference to FIG. 3 to FIGS. 6A and 6B.

FIG. 3 is a sectional view of the magnetic read write head 10illustrated in FIG. 2, in the YZ cross-sectional surface orthogonal tothe ABS 11S, and FIG. 4 is an enlarged sectional view illustrating apart of FIG. 3 in an enlarged manner. FIG. 5 is a schematic diagramillustrating a planar structure of a main part of the magnetic readwrite head 10 viewed from an arrow V direction illustrated in FIG. 2.FIGS. 6A and 6B each illustrates a part of an end surface exposed on theABS 11S in an enlarged manner. Note that an up-arrow M illustrated inFIG. 3 and FIG. 4 indicates a direction in which the magnetic disk 2moves relative to the magnetic read write head 10.

In the following description, dimensions in the X-axis direction, theY-axis direction, and the Z-axis direction are referred to as “width”,“height” or “length”, and “thickness”, respectively, and a closer sideand a farther side to/from the ABS 11S in the Y-axis direction arereferred to as “forward” and “backward”, respectively. Moreover, thedirection of the arrow M is referred to as “trailing side”, a directionopposite to the direction of the arrow M is referred to as “leadingside”, and the X-axis direction and the Z-axis direction are referred toas “cross track direction” and “down track direction”, respectively.

The magnetic read write head 10 has a stacked structure including aninsulating layer 13, a read head section 14, a write head section 16,and a protective layer 17 that are stacked in order on the slider 11.Each of the read head section 14 and the write head section 16 has anend surface exposed on the ABS 11S.

The read head section 14 uses magneto-resistive effect (MR) to perform aread process. The read head section 14 may be configured by stacking,for example, a lower shield layer 21, an MR element 22, and an uppershield layer 23 in this order on the insulating layer 13.

The lower shield layer 21 and the upper shield layer 23 may berespectively formed of, for example, a soft magnetic metal material suchas NiFe (nickel iron alloy), and are disposed to face each other withthe MR element 22 in between in the stacking direction (in the Z-axisdirection). As a result, these layers each exhibit a function to protectthe MR element 22 from the influence of an unnecessary magnetic field.

One end surface of the MR element 22 is exposed on the ABS 11S, and theother end surfaces thereof are in contact with an insulating layer 24filling a space between the lower shield layer 21 and the upper shieldlayer 23. The insulating layer 24 is formed of an insulating materialsuch as Al₂O₃ (aluminum oxide), AlN (aluminum nitride), SiO₂ (silicondioxide), and DLC (diamond-like carbon).

The MR element 22 functions as a sensor to read magnetic informationwritten in the magnetic disk 2. The MR element 22 is, for example, a CPP(Current Perpendicular to Plane)-GMR (Giant Magnetoresistive) element,sense current of which flows inside thereof in a stacking direction. Inthis case, the lower shield layer 21 and the upper shield layer 23 eachfunction as an electrode to supply the sense current to the MR element22.

In the read head section 14 with such a structure, a magnetizationdirection of a free layer (not illustrated) included in the MR element22 changes in response to a signal magnetic field from the magnetic disk2. Thus, the magnetization direction of the free layer shows a changerelative to a magnetization direction of a pinned layer (notillustrated) also included in the MR element 22. When the sense currentflows through the MR element 22, the relative change of themagnetization direction appears as the change of the electricresistance, and thus, the signal magnetic field is detected with use ofthe change and the magnetic information is accordingly read out.

On the read head section 14, an insulating layer 25, an intermediateshield layer 26, and an insulating layer 27 are stacked in order. Theintermediate shield layer 26 functions to prevent a magnetic field thatis generated in the write head section 16 from reaching the MR element22, and may be formed of, for example, a soft magnetic metal materialsuch as NiFe. The insulating layers 25 and 27 may be formed of thesimilar material to that of the insulating layer 24, for example.

The write head section 16 is a perpendicular magnetic write headperforming a writing process of thermally-assisted magnetic recordingsystem. The write head section 16 has, for example, a lower yoke layer28, a leading shield 29 and a connecting layer 30, a cladding layer 31,a waveguide 32, and a cladding layer 33 in order on the insulating layer27. Note that the leading shield 29 may be omitted from the structure.

The lower yoke layer 28, the leading shield 29, and the connecting layer30 are each formed of a soft magnetic metal material such as NiFe. Theleading shield 29 is located at the frontmost end of the upper surfaceof the lower yoke layer 28 in such a manner that one end surface thereofis exposed on the ABS 11S. The connecting layer 30 is located at thebackward of the leading shield 29 on the upper surface of the lower yokelayer 28.

The cladding layer 31 is provided so as to cover the lower yoke layer28, the leading shield 29, and the connecting layer 30.

The waveguide 32 provided on the cladding layer 31 extends in adirection (the Y-axis direction) orthogonal to the ABS 11S, one endsurface thereof is exposed on the ABS 11S, and the other end surfacethereof is exposed at the backward thereof, for example. Note that thefront end surface of the waveguide 32 may be located at a positionreceded from the ABS 11S without being exposed on the ABS 11S. Thewaveguide 32 is formed of a dielectric material allowing laser light topass therethrough. Specifically, the waveguide 32 may be formed of amaterial essentially containing one or more of, for example, SiC, DLC,TiOx (titanium oxide), TaOx (tantalum oxide), SiNx (silicon nitride),SiO_(x)N_(y) (silicon oxynitride), Si (silicon), zinc selenide (ZnSe),NbOx (niobium oxide), GaP (gallium phosphide), ZnS (zinc sulfide), ZnTe(zinc telluride), CrOx (chromium oxide), FeOx (iron oxide), CuOx (copperoxide), SrTiOx (strontium titanate), BaTiOx (barium titanate), Ge(germanium), and C (diamond). Essentially containing means that theabove-described materials are contained as main components, and othermaterials may be contained as subcomponents (for example, impurity) aslong as having a refractive index higher than those of the claddinglayers 31 and 33. The waveguide 32 allows laser light from a laser diode60 (described later) to propagate toward the ABS 11S. Incidentally,although the cross-sectional shape parallel to the ABS 11S of thewaveguide 32 is a rectangular as illustrated in FIG. 6, for example, itmay have other shapes.

The cladding layers 31 and 33 are each formed of a dielectric materialhaving a refractive index, with respect to laser light propagatingthrough the waveguide 32, lower than that of the waveguide 32. Thecladding layers 31 and 33 may be formed of a material essentiallycontaining one or more of, for example, SiOx (silicon oxide), Al₂O₃(aluminum oxide), AlN (aluminum nitride), BeO (beryllium oxide), SiC(silicon carbide), and DLC (diamond-like carbon). Essentially containingmeans that the above-described materials are contained as maincomponents, and the other materials may be contained as subcomponents(for example, impurity) as long as having a refractive index lower thanthat of the waveguide 32.

The write head section 16 further includes a plasmon generator 34provided above the front end of the waveguide 32 with the cladding layer33 in between, and a magnetic pole 35 provided above the plasmongenerator 34.

The plasmon generator 34 includes a first region 341 and a second region342 located backward thereof. The first region 341 includes an endsurface 34AS exposed on the ABS 11S. The second region 342 is coupledwith the other end of the first region 341 opposite to the ABS 11S at aposition P1 and has a volume greater than that of the first region 341,for example.

The first region 341 extends backward from the ABS 11S to the positionP1 over a length L1 while maintaining a constant area of across-sectional surface (see FIG. 6) parallel to the ABS 11S, forexample. The position P1 is a position of a boundary between the firstregion 341 and the second region 342. The length L1 of the first region341 is preferably 40 nm or more and 100 nm or less, for example. Inaddition, a thickness T1 of the first region 341 is, for example, 10 nmor more and 80 nm or less.

As illustrated in FIG. 5, the second region 342 has a width W2 largerthan a width W1 of the first region 341. The thickness of the secondregion 342 is equal to the thickness of the first region 341, forexample. The second region 342 is coupled with the first region 341 atthe position P1 and extends backward.

The material of the plasmon generator 34 is a metal material(hereinafter, referred to as a first metal material) containing one ormore of, for example, Pd (palladium), Pt (platinum), Rh (rhodium), Ir(iridium), Ru (ruthenium), Au (gold), Ag (silver), Cu (copper), andaluminum (Al). Among them, Au, Ag, and Cu are more preferable, and Au ismost preferable. This is because it is excellent in chemical stability,and more efficiently generates near-field light NF (described later).Note that the material of the first region 341 is desirably the same asthat of the second region 342. This is to efficiently generate thenear-field light NF. In addition, this is to avoid complication inmanufacturing.

An adhesion layer 70 is provided around the plasmon generator 34. Theadhesion layer 70 includes a pair of adhesion regions 70L and 70R thatare located both adjacent to the plasmon generator 34 in the cross trackdirection (the X-axis direction) and an adhesion region 70B that islocated backward of the plasmon generator 34. In other words, both endfaces 34TL and 34TR in the cross track direction of the plasmongenerator 34 are in close contact with the adhesion regions 70L and 70R,respectively. More specifically, an end face 341TL of the first region341 and an end face 342TL of the second region 342 are in close contactwith the adhesion region 70L, and an end face 341TR of the first region341 and an end face 342TR of the second region 342 are in close contactwith the adhesion region 70R. Front ends 70L1 and 70R1 of the adhesionregions 70L and 70R are exposed on the ABS 11S. In addition, a backwardend face 34BS of the plasmon generator 34 is in close contact with theadhesion region 70B. The adhesion layer 70 is essentially formed of oneor more elements selected from a group configured of, for example, Ir(iridium), Pt (platinum), Cr (chromium), Pd (palladium), Co (cobalt), Ni(nickel), and Fe (iron). A thickness of each of the adhesion regions 70Land 70R is equal to the thickness of the first region 341, for example.Further, a width of each of the adhesion regions 70L and 70R is 0.5 nmor more and 10 nm or less, for example.

Adhesion force between the adhesion layer 70 and the plasmon generator34 is desirably greater than adhesion force between the cladding layer33 and the plasmon generator 34. The adhesion force described here isdefined by a magnitude of work of adhesion W_(ad) that indicatesdifficulty of detachment between the components in contact with eachother. For example, when two kinds of materials A and B are bonded, thework of adhesion W_(ad) that is energy necessary for detaching thebonded interface is roughly estimated from magnitude of surface energy γof each of materials A and B. Specifically, the work of adhesion W_(ad)is represented by the following expression (1) (Dupre equation).Incidentally, γ_(A) represents the surface energy of the material A,γ_(B) represents the surface energy of the material B, and γ_(AB)represents interface energy at the interface between the material A andthe material B.W _(ad)=γ_(A)+γ_(B)−γ_(AB)  (1)

Incidentally, γ_(AB) is represented by the following expression (2) withuse of γ_(A) and γ_(B).γ_(AB)=γ_(A)+γ_(B)−2φ(γ_(A)·γ_(B))^(1/2)  (2)where φ represents a mutual correlation coefficient between two phases,and is a value in a range of about 0.5 to about 1.2. Accordingly, thework of adhesion W_(ad) is represented by the following expression (3)from the expression (2).W _(ad)˜2×(γ_(A)·γ_(B))^(1/2)  (3)

The adhesiveness is higher as the material has larger work of adhesionW_(ad). Therefore, from the expression (3), an interface with highadhesiveness is allowed to be formed by using a material having largesurface energy γ. The magnitude of the surface energy γ of majormaterials is illustrated in the following table 1.

TABLE 1 Surface energy γ of major material (mJ/m²) Al 1140 Cu 1790 Ag1240 Au 1500 Ni 2380 Co 2470 Fe 2600 Pd 2000 Pt 2490 Al₂O₃  892 SiO₂ 200to 400

The adhesion layer 70 is formed of a material that allows both of theadhesion force in the case where the adhesion layer 70 and the plasmongenerator 34 are bonded and the adhesion force in the case where theadhesion layer 70 and the cladding layer 33 are bonded to be greaterthan the adhesion force in the case where the cladding layer 33 and theplasmon generator 34 are bonded. In other words, the work of adhesionbetween the material of the cladding layer 33 and the material of theadhesion layer 70 and the work of adhesion between the material of theadhesion layer 70 and the material of the plasmon generator 34 are madelarger than the work of adhesion between the material of the claddinglayer 33 and the material of the plasmon generator 34. Therefore, forexample, when SiO₂ is selected as the material of the cladding layer 33and Au (gold) is selected as the material of the plasmon generator 34,Ni (nickel), Fe (iron), Co (cobalt), Pd (palladium), Pt (platinum), andthe like that have the surface energy higher than that of SiO₂ and Auare suitable as the adhesion material configuring the adhesion layer 70.

Note that, as with a modification (a first modification) illustrated inFIG. 6B, the adhesion layer 70 may further include an adhesion region70U that is formed so as to be in close contact with an upper surface ofthe first region 341.

The first region 341 of the plasmon generator 34 is distanced from afirst layer 351 (described later) of the magnetic pole 35, and a gaplayer GP is provided therebetween. One end of the gap layer GP isexposed on the ABS 11S, and for example, the gap layer GP extendsbackward from the ABS 11S to a position P2 that is located backward ofthe position P1 over the length L2. For example, the gap layer GP isessentially formed of one or more dielectric materials selected fromSiO₂, Al₂O₃, MgO, ZnO, TaSiO, MgF₂, SiON, AlON, and ITO. With such a gaplayer GP provided, the first region 341 is surrounded by the claddinglayer 33, and is thus distanced from the front end of the waveguide 32and the front end of the first layer 351 of the magnetic pole 35. Thethickness T2 of the gap layer GP is, for example, 10 nm or more and 50nm or less.

A space at the rear of the gap layer GP is occupied by a third region343 that configures a part of the plasmon generator 34. The third region343 is so provided as to cover at least a part of the second region 342,and a front end face of the third region 343 is in contact with abackward end face of the gap layer GP at the position P2. A fourthregion 344 is further provided on the third region 343. For example, thefourth region 344 extends backward from the position P2, and covers apart or all of the third region 343. In this way, the second to fourthregions 342 to 344 that have a volume sufficiently greater than that ofthe first region 341 having one end exposed on the ABS 11S function as aheatsink that efficiently dissipates heat generated by the plasmongenerator 34 during operation.

The magnetic pole 35 has a structure in which the first layer 351 and asecond layer 352 are stacked in order on the plasmon generator 34. Thefirst layer 351 has an end face 35S1 exposed on the ABS 11S, and acounter face 35S2 that faces the first region 341 of the plasmongenerator 34 with the gap layer GP in between. The counter face 35S2 isin contact with, for example, the entire upper surface of the gap layerGP.

The second layer 352 extends backward from a position receded from theABS 11S by a length L4 (>L1). Both of the first layer 351 and the secondlayer 352 are formed of, for example, a magnetic material with highsaturation flux density such as iron-based alloy. Examples of theiron-based alloy include FeCo (iron cobalt alloy), FeNi (iron nickelalloy), and FeCoNi (iron cobalt nickel alloy). Incidentally, although across-sectional shape of the first layer 351 parallel to the ABS 11S is,for example, an inverted trapezoid as illustrated in FIGS. 6A and 6B,may be other shapes.

The plasmon generator 34 generates near-field light NF from the ABS 11S,based on the laser light that has propagated through the waveguide 32.The magnetic pole 35 stores therein magnetic flux generated in a coil 41(described later), releases the magnetic flux from the ABS 11S, therebygenerating a write magnetic field for writing magnetic information intothe magnetic disk 2. The plasmon generator 34 and the first layer 351are embedded in the cladding layer 33.

As illustrated in FIG. 3, the write head section 16 further includes aconnecting layer 36 embedded in the cladding layer 33 at the backward ofthe plasmon generator 34 and the magnetic pole 35, and a connectinglayer 37 that is so provided as to be in contact with an upper surfaceof the connecting layer 36. The connecting layers 36 and 37 are locatedabove the connecting layer 30 and are formed of a soft magnetic metalmaterial such as NiFe. Note that the connecting layer 36 is magneticallyconnected by a connection section (not illustrated) that may be formedof, for example, a soft magnetic metal material such as NiFe.

As illustrated in FIG. 3, on the cladding layer 33, an insulating layer38 is provided so as to fill surroundings of the second layer 352 of themagnetic pole 35. An insulating layer 39 and the coil 41 that is formedin spiral around the connecting layer 37 are stacked in order on theinsulating layer 38. The coil 41 is intended to generate recording-usemagnetic flux by a write current flowing therethrough, and is formed ofa high conductive material such as Cu (copper) and Au (gold). Theinsulating layers 38 and 39 are each formed of an insulating materialsuch as Al₂O₃, AlN, SiO₂ and DLC. The insulating layer 38, theinsulating layer 39, and the coil 41 are covered with an insulatinglayer 42, and further, an upper yoke layer 43 is so provided as to coverthe insulating layer 42. The insulating layer 42 may be formed of, forexample, a non-magnetic insulating material flowing during being heated,such as a photoresist or a spin on glass (SOG). The insulating layers38, 39, and 42 each electrically separate the coil 41 from itssurroundings. The upper yoke layer 43 may be formed of a soft magneticmaterial with high saturation flux density such as CoFe, the frontsection thereof is connected to the second layer 352 of the magneticpole 35, and a part of the backward section is connected to theconnecting layer 37. In addition, the front end surface of the upperyoke layer 43 is located at a position recessed from the ABS 11S.

In the write head section 16 having the foregoing structure, by thewrite current flowing through the coil 41, magnetic flux is generatedinside a magnetic path that is mainly configured by the leading shield29, the lower yoke layer 28, the connecting layers 30, 36, and 37, theupper yoke layer 43, and the magnetic pole 35. Accordingly, a signalmagnetic field is generated near the end surface of the magnetic pole 35exposed on the ABS 11S, and the signal magnetic field reaches apredetermined region of the recording surface of the magnetic disk 2.

Further, in the magnetic read write head 10, for example, the protectivelayer 17 that may be formed of a material similar to that of thecladding layer 33 is so formed as to cover the entire upper surface ofthe write head section 16. In other words, the cladding layer 33 and theprotective layer 17 that are each formed of a material having a lowerrefractive index and higher thermal conductivity compared with thewaveguide 32 are so provided as to collectively surround the waveguide32, the plasmon generator 34, and the magnetic pole 35.

[3. Outline of Method of Manufacturing Magnetic Read Write Head]

Next, with reference to FIG. 7 and FIG. 8 in addition to FIG. 4, outlineof a method of manufacturing the magnetic read write head 10 will bedescribed. FIG. 7 and FIG. 8 are perspective views each illustrating oneprocess of the method of manufacturing the magnetic read write head 10.

First, as illustrated in FIG. 7, a wafer 11ZZ that may be formed of, forexample, AlTiC is prepared. The wafer 11ZZ is to be a plurality ofsliders 11 finally. After that, a plurality of magnetic read write heads10 are formed in array on the wafer 11ZZ in the following way.

The magnetic read write head 10 is manufactured mainly by sequentiallyforming and stacking a series of components by using an existing thinfilm process. Examples of the existing thin film process include filmforming technique such as electrolytic plating and sputtering,patterning technique such as photolithography, etching technique such asdry etching and wet etching, and polishing technique such as chemicalmechanical polishing (CMP).

In this case, first, the insulating layer 13 is formed on the wafer11ZZ. Next, the lower shield layer 21, the MR element 22 and theinsulating layer 24, and the upper shield layer 23 are formed bystacking in this order on the insulating layer 13 to form the read headsection 14. Subsequently, the insulating layer 25, the intermediateshield layer 26, and the insulating layer 27 are stacked in order on theread head section 14.

After that, the lower yoke layer 28, the leading shield 29 and theconnecting layer 30, the cladding layer 31, the waveguide 32, thecladding layer 33, the plasmon generator 34, the adhesion layer 70, thegap layer GP, the magnetic pole 35, and the connecting layers 36 and 37are formed in order on the insulating layer 27. Note that the structurefrom which the leading shield 29 may be omitted may be employed.Further, by performing a planarization process after the insulatinglayer 38 is formed so as to cover the entire surface, the upper surfacesof the magnetic pole 35, the insulating layer 38, and the connectinglayer 37 are planarized, and the coil 41 embedded by the insulatinglayers 39 and 42 is then formed. Moreover, the upper yoke layer 43connected with the magnetic pole 35 and the connecting layer 37 isformed to complete the write head section 16. After that, the protectivelayer 17 is formed on the write head section 16, and as a result, theplurality of magnetic read write heads 10 in a phase before formation ofthe ABS 11S are formed in an array on the wafer 11ZZ (FIG. 7).

After that, as illustrated in FIG. 8, the wafer 11ZZ is cut to form aplurality of bars 11Z. The plurality of magnetic read write heads 10 areformed in line in each of the bars 11Z. Further, one side surface of thebar 11Z, that is, a side surface of the stacked structure from theslider 11 to the protective layer 17 is collectively polished by the CMPmethod or the like to form the ABS 11S. At that time, it is formed sothat the length L1 of the first region 341 of the plasmon generator 34has a predetermined length.

After the ABS 11S is formed, a protective film formed of anon-conductive material such as DLC may be formed so as to cover theentire ABS 11S.

[4. Method of Forming Gap Layer and Adhesion Layer]

Next, with reference to FIG. 9 to FIG. 13, detail of a method of formingthe adhesion layer 70 is described below. FIG. 9 to FIG. 13 are eachsectional views parallel to the ABS 11S.

First, as illustrated in FIG. 9, a metallic layer 34Z1 that is to be thefirst region 341 and the second region 342 of the plasmon generator 34is collectively formed, with use of the above-described metal material,on a cladding material layer 33Z1 that configures a part of the claddinglayer 33. Note that the first region 341 and the second region 342 maybe formed individually.

Then, as illustrated in FIG. 10, the metallic layer 34Z1 is patterned toform the first region 341 and the second region 342 (not illustrated inFIG. 10). Further, a metallic layer 70Z that is to be adhesion layer 70is formed so as to cover the entire surface. At this time, the metalliclayer 70Z is allowed to be in close contact with the end faces 341TL and341TR of the first region 341, the end faces 342TL and 342TR of thesecond region 342 (that are not illustrated in FIG. 10), and thebackward end face 34BS (not illustrated in FIG. 10). Moreover, themetallic layer 70Z is formed so that parts covering the respective endfaces 341TL, 341TR, 342TL, 342TR, and 34BS have a predeterminedthickness.

After that, as illustrated in FIG. 11, the metallic layer 70Z is milledfrom above to remove the metallic layer 70Z other than the partscovering the respective end faces 341TL, 341TR, 342TL, 342TR, and 34BS.As a result, the adhesion layer 70 including the adhesion regions 70L,70R, and 70B is obtained. Subsequently, as illustrated in FIG. 12, acladding material layer 33Z2 that configures the other parts of thecladding layer 33 is so formed as to cover the entire surface. Finally,the cladding material layer 33Z2 is entirely polished to be planarized,and the upper surfaces of the first region 341 and the second region 342(not illustrated in FIG. 13) are exposed as illustrated in FIG. 13.

[5. Detailed Configuration of Light Source Unit]

The light source unit 50 is described in more detail with reference toFIG. 3 again. As illustrated in FIG. 3, the light source unit 50provided at the rear of the magnetic read write head 10 includes thelaser diode 60 as a light source emitting laser light, and, for example,a rectangular parallelepiped supporting member 51 supporting the laserdiode 60.

The supporting member 51 is formed of, for example, a ceramic materialsuch as Al₂O₃·TiC. As illustrated in FIG. 3, the supporting member 51includes a bonded surface 51A to be bonded to a back surface 11B of theslider 11, and a light source mounting surface 51C orthogonal to thebonded surface 51A. The light source mounting surface 51C is parallel tothe element forming surface 11A. The laser diode 60 is mounted on thelight source mounting surface 51C. The supporting member 51 desirablyhas a function of a heatsink dissipating heat generated by the laserdiode 60, in addition to the function to support the laser diode 60.

Laser diodes generally used for communication, for optical disc storage,or for material analysis, for example, InP-based, GaAs-based, orGaN-based one may be used as the laser diode 60. The wavelength of thelaser light emitted from the laser diode 60 may be any value within therange of, for example, 375 nm to 1.7 μm. Specifically, it may be a laserdiode of InGaAsP/InP quaternary mixed crystal with the emissionwavelength region of 1.2 to 1.67 μm. As illustrated in FIG. 3, the laserdiode 60 has a multilayer structure including a lower electrode 61, anactive layer 62, and an upper electrode 63. For example, an n-typesemiconductor layer 65 including n-type AlGaN is interposed between thelower electrode 61 and the active layer 62, and for example, a p-typesemiconductor layer 66 including p-type AlGaN is interposed between theactive layer 62 and the upper electrode 63. On each of two cleavagesurfaces of the multilayer structure, a reflective layer 64 formed ofSiO₂, Al₂O₃, or the like is provided to totally reflect light and exciteoscillation. In the reflective layer 64, an opening for emitting laserlight is provided at a position including an emission center 62A of theactive layer 62. The relative positions of the light source unit 50 andthe magnetic read write head 10 are fixed by bonding the bonded surface51A of the supporting member 51 to the back surface 11B of the slider 11in such a manner that the emission center 62A and the backward endsurface 32A of the waveguide 32 are coincident with each other. Athickness T_(LA) of the laser diode 60 is, for example, about 60 to 200μm. When a predetermined voltage is applied between the lower electrode61 and the upper electrode 63, laser light is emitted from the emissioncenter 62A of the active layer 62, and then enters the backward endsurface 32A of the waveguide 32. Incidentally, the laser light emittedfrom the laser diode 60 is preferably polarized light of a TM mode whoseelectric field oscillates in a direction perpendicular to the surface ofthe active layer 62. The laser diode 60 may be driven with use of apower source in the magnetic disk unit. The magnetic disk unit generallyincludes a power source generating a voltage of about 5 V, for example,and the voltage generated by the power source is sufficient to drive thelaser diode 60. In addition, the laser diode 60 consumes power of, forexample, about several tens mW, which is sufficiently covered by thepower source in the magnetic disk unit.

[6. Control Circuit of Magnetic Disk Unit and Operation]

With reference to FIG. 14, the circuit configuration of the controlcircuit of the magnetic disk unit illustrated in FIG. 1 and theoperation of the magnetic read write head 10 will be described below.The control circuit includes a control LSI (large-scale integration)100, a ROM (read only memory) 101 connected to the control LSI 100, awrite gate 111 connected to the control LSI 100, and a write circuit 112connecting the write gate 111 to the coil 41. The control circuitfurther includes a constant current circuit 121 connected to the MRelement 22 and the control LSI 100, an amplifier 122 connected to the MRelement 22, and a demodulation circuit 123 connected to the output endof the amplifier 122 and the control LSI 100. The control circuitfurther includes a laser control circuit 131 connected to the laserdiode 60 and the control LSI 100, and a temperature detector 132connected to the control LSI 100.

Here, the control LSI 100 provides write data and a write control signalto the write gate 111. Moreover, the control LSI 100 provides a readcontrol signal to the constant current circuit 121 and the demodulationcircuit 123, and receives read data output from the demodulation circuit123. In addition, the control LSI 100 provides a laser ON/OFF signal andan operation current control signal to the laser control circuit 131.

The temperature detector 132 detects the temperature of the magneticrecording layer of the magnetic disk 2 to transmit information of thetemperature to the control LSI 100. The ROM 101 holds a control tableand the like to control an operation current value to be supplied to thelaser diode 60. At the time of write operation, the control LSI 100supplies the write data to the write gate 111. The write gate 111supplies the write data to the write circuit 112 only when the writecontrol signal instructs to perform the write operation. The writecircuit 112 allows the write current to flow through the coil 41according to the write data. As a result, the write magnetic field isgenerated from the magnetic pole 35, and data is written into themagnetic recording layer of the magnetic disk 2 by the write magneticfield.

At the time of read operation, the constant current circuit 121 suppliesa constant sense current to the MR element 22 only when the read controlsignal instructs to perform the read operation. The output voltage ofthe MR element 22 is amplified by the amplifier 122, and is thenreceived by the demodulation circuit 123. The demodulation circuit 123demodulates the output of the amplifier 122 to generate read data to beprovided to the control LSI 100 when the read control signal instructsto perform the read operation.

The laser control circuit 131 controls the supply of the operationcurrent to the laser diode 60 based on the laser ON/OFF signal, andcontrols the value of the operation current supplied to the laser diode60 based on the operation current control signal. The operation currentequal to or larger than an oscillation threshold is supplied to thelaser diode 60 by the control of the laser control circuit 131 when thelaser ON/OFF signal instructs to perform the ON operation. As a result,the laser light is emitted from the laser diode 60 and then the laserlight propagates through the waveguide 32. Subsequently, the near-fieldlight NF (described later) is generated from the tip section 34G of theplasmon generator 34, a part of the magnetic recording layer of themagnetic disk 2 is heated by the near-field light NF, and thus thecoercivity in that part is lowered. At the time of writing, the writemagnetic field generated from the magnetic pole 35 is applied to thepart of the magnetic recording layer with lowered coercivity, andtherefore data recording is performed.

The control LSI 100 determines a value of the operation current of thelaser diode 60 with reference to the control table stored in the ROM101, based on the temperature of the magnetic recording layer of themagnetic disk 2 measured by the temperature detector 132 and the like,and controls the laser control circuit 131 with use of the operationcurrent control signal in such a manner that the operation current ofthe value is supplied to the laser diode 60. The control table includes,for example, the oscillation threshold of the laser diode 60 and dataindicating temperature dependency of light output-operation currentproperty. The control table may further include data indicating arelationship between the operation current value and the increasedamount of the temperature of the magnetic recording layer heated by thenear-field light NF, and data indicating temperature dependency of thecoercivity of the magnetic recording layer.

The control circuit illustrated in FIG. 13 has a signal system tocontrol the laser diode 60, that is, a signal system of the laser ON/OFFsignal and the operation current control signal, independent of thecontrol signal system of write-read operation, and therefore, morevarious conduction modes to the laser diode 60 are achievable, inaddition to the conduction to the laser diode 60 simply operated inconjunction with the write operation. Note that the configuration of thecontrol circuit of the magnetic disk unit is not limited to thatillustrated in FIG. 14.

Subsequently, a principle of near-field light generation in the presentembodiment and a principle of thermally-assisted magnetic recording withuse of the near-field light will be described with reference to FIG. 4.

Laser light 45 which has been emitted from the laser diode 60 propagatesthrough the waveguide 32 to reach near the plasmon generator 34. At thistime, the laser light 45 is totally reflected by an evanescent lightgenerating surface 32C that is an interface between the waveguide 32 anda buffer section 33A (a section between the waveguide 32 and the plasmongenerator 34, of the cladding layer 33), and therefore evanescent light46 leaking into the buffer section 33A is generated. After that, theevanescent light 46 couples with charge fluctuation on a surface plasmonexciting surface 34S1 facing the waveguide 32, of the plasmon generator34 to induce a surface plasmon polariton mode. As a result, surfaceplasmons 47 are excited on the surface plasmon exciting surface 34S1.The surface plasmons 47 propagate on the surface plasmon excitingsurface 34S1 toward the ABS 11S.

The surface plasmons 47 eventually reach the ABS 11S, and as a result,the near-field light NF is generated on the tip section 34G. Thenear-field light NF is irradiated toward the magnetic disk 2 (notillustrated in FIG. 4) and reaches the surface of the magnetic disk 2 toheat a part of the magnetic recording layer of the magnetic disk 2. As aresult, the coercivity at the heated part of the magnetic recordinglayer is lowered. In the thermally-assisted magnetic recording, thewrite magnetic field generated by the magnetic pole 35 is applied to thepart of the magnetic recording layer with the coercivity thus lowered,to perform data writing.

[7. Effects]

As described above, the magnetic read write head 10 of the presentembodiment has the adhesion layer 70 that is formed in close contactwith the end faces 34TL and 34TR of the plasmon generator 34. Therefore,even when the temperature of the plasmon generator 34 is increasedduring operation, displacement of the shape of the first region 341 andthe second region 342 is suppressed, and thus agglomeration of the firstregion 341 is difficult to occur. In other words, even when the volumeof the first region 341, temperature of which becomes the highest duringoperation, is smaller than the volume of the second region 342, thepresence of the adhesion layer 70 prevents the first region 341 frombeing pulled by the second region 342 and being receded from the ABS11S. On the other hand, since the first region 341 and the second region342 are coupled with each other, the surface plasmons generated byevanescent coupling between the light propagating through the waveguide32 and the second region 342 efficiently propagate through the firstregion 341. In this way, according to the magnetic read write head 10,the magnetic disk unit provided therewith, and the like in the presentembodiment, it is possible to prevent agglomeration of the first region341 during operation, and it is possible to generate the near-fieldlight NF efficiently. Consequently, the magnetic recording with higherdensity becomes possible and improvement of product lifetime is alsoexpected.

In the present embodiment, in particular, the adhesion layer 70 coversthe adhesion region 70U that covers the upper surface of the firstregion 341, which makes it possible to sufficiently suppress occurrenceof the agglomeration of the first region 341, and thus it is morepreferable.

[8. Modification]

(Second Modification)

Next, a second modification of the present embodiment is described withreference to FIG. 15. In the above-described embodiment, the pair ofadhesion regions 70L and 70R that is entirely in close contact with theend faces 34TL and 34TR of the plasmon generator 34 is provided. Incontrast, in the present modification, the pair of the adhesion regions70L and 70R are formed of two parts separated from each other.

Specifically, for example, as illustrated in FIG. 15, the adhesionregion 70L is separated into a front region 71L that is in close contactwith the first region 341 and a rear region 72L that is in close contactwith the second region 342. Likewise, the adhesion region 70R isseparated into a front region 71R that is in close contact with thefirst region 341 and a rear region 72R that is in close contact with thesecond region 342. However, the front regions 71L and 71R are preferablyin close contact with a part of the second region 342. For example, thefront ends 71L 1 and 71R1 of the front regions 71L and 71R are exposedon the ABS 11S, whereas the position P3 of backward ends 71L2 and 71R2of the front regions 71L and 71R is preferably located backward of theposition P1 and in front of the position P2. In other words, the frontregions 71L and 71R extend along the outer edge of the plasmon generator34 from the ABS 11S as a base point to the position P3 (for example, theposition away from the position P1 by 30 nm) located backward of theposition P1. Moreover, the rear regions 72L and 72R extend backward fromthe position P2.

In this example, for convenience, the second region 342 is separatedinto a front region 342A located in front of the position P2 and a rearregion 342B located backward of the position P2. The front region 342Ais a region occupying from the position P1 to the position P2, and thegap layer GP is provided on the top surface thereof (see FIG. 3). On theother hand, the rear region 342B is a region provided with the thirdregion 343 thereon. The rear regions 72L and 72R of the adhesion regions70L and 70R are in close contact with the end faces 342TLB and 342TRB ofthe rear region 342B of the second region 342, respectively.

A pair of sacrifice layers 80L and 80R is provided between the frontregion 71L and the rear region 72L that are separated from each other.The pair of sacrifice layers 80L and 80R is in close contact with theend faces 342TLA and 342TRA of the front region 342A of the secondregion 342, respectively. For example, the pair of sacrifice layers 80Land 80R is essentially formed of the material same as that of thecladding layer 33. Accordingly, adhesion force between the adhesionregion 70L (the front region 71L and the rear region 72L) and theplasmon generator 34 is greater than adhesion force between thesacrifice layer 80L and the plasmon generator 34. Likewise, adhesionforce between the adhesion region 70R (the front region 71R and the rearregion 72R) and the plasmon generator 34 is greater than adhesion forcebetween the sacrifice layer 80R and the plasmon generator 34. Thesacrifice layers 80L and 80R extend from the position P3 to the positionP2 in the height direction (the Y-axis direction). As described above,for example, the position P3 is away from the position P1 by 30 nm. Itis conceivable that when the sacrifice layers 80L and 80R are providedat positions away from the backward end of the first region 341 by about30 nm, it is possible to avoid the first region 341 from being affectedby the agglomeration of the second region 342 that occurs near theinterface between the sacrifice layers 80L and 80R and the second region342.

In the present modification, even when the temperature of the plasmongenerator 34 is increased during operation, detachment between thesacrifice layers 80L and 80R and the end faces 342TLA and 342TRApreferentially occurs before detachment between the adhesion regions71L, 71R, 72L, and 72R and the end faces 341TL, 341TR, 342TLB, and342TRB occurs. Therefore, agglomeration of the first region 341 that isin close contact with the adhesion regions 70L and 70R is suppressed.Specifically, even when the volume of the first region 341, temperatureof which becomes the highest during operation, is smaller than thevolume of the second region 342, the presence of the adhesion regions70L and 70R and the sacrifice layers 80L and 80R prevents the firstregion 341 from being pulled by the second region 342 and being recededfrom the ABS 11S. In this way, in the present modification, as comparedwith the above-described embodiment, even when the temperature of theplasmon generator 34 is high, the agglomeration of the first region 341is allowed to be prevented, and the near-field light NF is allowed to beefficiently generated. Therefore, the magnetic recording with higherdensity becomes possible, and improvement of product lifetime isexpected.

(Third Modification)

Then, a third modification of the present embodiment is described withreference to FIG. 16. In the above-described embodiment, the pair ofadhesion regions 70L and 70R that is entirely in close contact with theend faces 34TL and 34TR of the plasmon generator 34 is provided. Incontrast, in the present modification, a pair of adhesion regions 73Land 73R as the adhesion layer 70 is provided only near the first region341 of the plasmon generator 34.

In the present modification, for example, the front ends 73L1 and 73R1of the adhesion regions 73L and 73R are exposed on the ABS 11S, whereasbackward ends 73L2 and 73R2 of the adhesion regions 73L and 73R arelocated at the position P3 that is located backward of the position P1and in front of the position P2. In other words, for example, theadhesion regions 73L and 73R extend along the outer edge of the plasmongenerator 34 from the ABS 11S as a base point to the position P3 (forexample, the position away from the position P1 by 30 nm) that islocated backward of the position P1. In addition, rear regions of theadhesion regions 73L and 73R are filled with the cladding layer 33 (notillustrated in FIG. 16).

Effects similar to those in the above-described embodiment areobtainable also in the present modification.

Hereinbefore, although the invention has been described with referenceto the embodiment, the invention is not limited to the above-describedembodiment, and various modifications may be made. For example, in thethermally-assisted magnetic recording head of the invention, theconfigurations (shapes, positional relationship, etc.) of the waveguide,the plasmon generator, the magnetic pole, and the like are not limitedto those described in the above-described embodiment, and athermally-assisted magnetic recording head having other configurationmay be employed.

The correspondence relationships between the reference numerals and thecomponents of the present embodiment are collectively illustrated asfollows.

1 . . . housing, 2 . . . magnetic disk, 3 . . . head arm assembly (HAA),4 . . . head gimbal assembly (HGA), 4A . . . magnetic head device, 4B .. . suspension, 5 . . . arm, 6 . . . driver, 7 . . . fixed shaft, 8 . .. bearing, 9 . . . spindle motor, 10 . . . magnetic read write head, 11. . . slider, 11A . . . element forming surface, 11B . . . back surface,11S . . . air bearing surface (ABS), 12 . . . element forming layer, 13. . . insulating layer, 14 . . . read head section, 16 . . . write headsection, 17 . . . protective layer, 21 . . . lower shield layer, 22 . .. MR element, 23 . . . upper shield layer, 24, 25, 27, 38, 39, 42 . . .insulating layer, 26 . . . intermediate shield layer, 28 . . . loweryoke layer, 29 . . . leading shield, 30, 36, 37 . . . connecting layer,31, 33 . . . cladding layer, 32 . . . waveguide, 34 . . . plasmongenerator, 341 . . . first region, 342 . . . second region, 34G . . .tip section, 34S1 . . . surface plasmon exciting surface, 35 . . .magnetic pole, 351 . . . first layer, 352 . . . second layer, 41 . . .coil, 43 . . . upper yoke layer, 45 . . . laser light, 46 . . .evanescent light, 47 . . . surface plasmon, 70 . . . adhesion layer, 80. . . sacrifice layer, 100 . . . LSI, 101 . . . ROM, 111 . . . writegate, 121 . . . constant current circuit, 122 . . . amplifier, 123 . . .demodulation circuit, 131 . . . laser control circuit, 132 . . .temperature detector, GP . . . gap layer, NF . . . near-field light.

What is claimed is:
 1. A thermally-assisted magnetic recording head,comprising: a magnetic pole having an end exposed on an air-bearingsurface; a waveguide; a plasmon generator having a first region and asecond region, the first region extending backward from the air-bearingsurface to a first position, the second region being coupled with thefirst region at the first position, extending backward from the firstposition, and having a width in a track-width direction, and the widthin the track-width direction of the second region being larger than awidth in the track-width direction of the first region; an adhesionlayer having an end exposed on the air-bearing surface and a firstadhesion region, the first adhesion region being in close contact withan end face in the track-width direction of the first region; and acladding layer located around the plasmon generator and the adhesionlayer, wherein adhesion force between the adhesion layer and the plasmongenerator is greater than adhesion force between the cladding layer andthe plasmon generator.
 2. The thermally-assisted magnetic recording headaccording to claim 1, wherein the adhesion layer further includes asecond adhesion region that is in close contact with an end face in thetrack-width direction of the second region and a backward end face ofthe second region.
 3. The thermally-assisted magnetic recording headaccording to claim 2, further comprising a sacrifice layer, wherein thefirst adhesion region and the second adhesion region are separated fromeach other, and the sacrifice layer is positioned between the firstadhesion region and the second adhesion region and faces a part of theend face in the track-width direction of the second region.
 4. Thethermally-assisted magnetic recording head according to claim 3, whereinthe adhesion force between the adhesion layer and the plasmon generatoris greater than adhesion force between the sacrifice layer and theplasmon generator.
 5. The thermally-assisted magnetic recording headaccording to claim 1, wherein the first adhesion region covers a topface of the first region.
 6. The thermally-assisted magnetic recordinghead according to claim 1, wherein a volume of the second region isgreater than a volume of the first region.
 7. The thermally-assistedmagnetic recording head according to claim 1, wherein the plasmongenerator consists essentially of one or more elements selected from agroup consisting of Au, Ag, and Cu.
 8. The thermally-assisted magneticrecording head according to claim 1, wherein the adhesion layer consistsessentially of one or more elements selected from a group consisting ofIr, Pt, Cr, Pd, Co, Ni, and Fe.
 9. The thermally-assisted magneticrecording head according to claim 3, wherein a material of the sacrificelayer is essentially same as a material of the cladding layer.
 10. Thethermally-assisted magnetic recording head according to claim 1, furthercomprising a gap layer made of a dielectric material, the gap layerbeing provided between the magnetic pole and the first region andextending backward from the air-bearing surface to a second positionthat is located backward of the first position, wherein the plasmongenerator is provided between the magnetic pole and the waveguide. 11.The thermally-assisted magnetic recording head according to claim 10,wherein the plasmon generator further includes a third region that is incontact with a backward end face of the gap layer at the second positionand covers a part of the second region.
 12. The thermally-assistedmagnetic recording head according to claim 11, wherein the plasmongenerator further includes a fourth region extending backward from thesecond position and covering a part or all of the third region.
 13. Thethermally-assisted magnetic recording head according to claim 11,wherein the plasmon generator further includes a fourth region extendingbackward from a fourth position that is located between the secondposition and the air-bearing surface, and covering a part of the gaplayer and a part or all of the third region.
 14. The thermally-assistedmagnetic recording head according to claim 10, wherein the gap layerconsists essentially of one or more materials selected from SiO₂, Al₂O₃,MgO, ZnO, TaSiO, MgF₂, SiON, AlON, and ITO.
 15. A head gimbal assembly,comprising: a magnetic head slider having a side surface, the sidesurface including the thermally-assisted magnetic recording headaccording to claim 1; and a suspension having an end, the end beingattached with the magnetic head slider.
 16. A head arm assembly,comprising: a magnetic head slider having a side surface, the sidesurface including the thermally-assisted magnetic recording headaccording to claim 1; a suspension having a first end and a second end,the first end being attached with the magnetic head slider; and an armsupporting the suspension at the second end thereof.
 17. A magnetic diskunit provided with a magnetic recording medium and a head arm assembly,the head arm assembly comprising: a magnetic head slider having a sidesurface, the side surface including the thermally-assisted magneticrecording head according to claim 1; a suspension having a first end anda second end, the first end being attached with the magnetic headslider; and an arm supporting the suspension at the second end thereof.